A judge formally signed an arrest warrant Monday charging Navarro-Canales as an adult with two counts of murder. Police have asked for the public's help in finding him.

In the affidavit for the arrest warrant, the Clark County Coroner's Office estimated that the victims were killed Tuesday evening in their apartment, CNN affiliate KLAS reported.

Police believe Navarro-Canales continued living in the unit with the dead bodies, the station reported. His brother was later found in the apartment's bathtub and his mother nearby with a knife in the center of her chest, it said.

The family threw a small party at their apartment for Navarro-Canales' 16th birthday on Monday, KLAS reported.

Police are asking anyone who knows of his whereabouts to call 911 immediately.